[jira] [Commented] (HADOOP-11301) [optionally] update jmx cache to drop old metrics

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-11301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14215622#comment-14215622 ] 

Hadoop QA commented on HADOOP-11301:
------------------------------------

{color:green}+1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12682047/HADOOP-11301.v01.patch
  against trunk revision 2fce6d6.

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:green}+1 tests included{color}.  The patch appears to include 1 new or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  There were no new javadoc warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new Findbugs (version 2.0.3) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in hadoop-common-project/hadoop-common.

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: https://builds.apache.org/job/PreCommit-HADOOP-Build/5093//testReport/
Console output: https://builds.apache.org/job/PreCommit-HADOOP-Build/5093//console

This message is automatically generated.

> [optionally] update jmx cache to drop old metrics
> -------------------------------------------------
>
>                 Key: HADOOP-11301
>                 URL: https://issues.apache.org/jira/browse/HADOOP-11301
>             Project: Hadoop Common
>          Issue Type: Improvement
>            Reporter: Maysam Yabandeh
>            Assignee: Maysam Yabandeh
>         Attachments: HADOOP-11301.v01.patch
>
>
> MetricsSourceAdapter::updateJmxCache() skips updating the info cache if no new metric is added since last time:
> {code}
>       int oldCacheSize = attrCache.size();
>       int newCacheSize = updateAttrCache();
>       if (oldCacheSize < newCacheSize) {
>         updateInfoCache();
>       }
> {code}
> This behavior is not desirable in some applications. For example nntop (HDFS-6982) reports the top users via jmx. The list is updated after each report. The previously reported top users hence should be removed from the cache upon each report request.
> In our production run of nntop we made a change to ignore the size check and always perform updateInfoCache. I am planning to submit a patch including this change. The feature can be enabled by a configuration parameter.



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